LTC3115-1 have hiccup mode?

Hi

I'm a DFAE in Japan. Our customer evaluates LTC3115-1 and faces similar to hiccup mode (Vo is up and down)  when Vin=4V, Vo=12V and IO>200mA. The power supply design spec is Vin=4V~32V, Vo=12V and Io=300mA. It seems that the load current that can be made to flow stably decreases as the input voltage decreases.  I don't find the word of "hiccup" on LTC3115-1 D/S. Could you please let me know how to improve?

Regards,

Hiroyuki

  • 0
    •  Analog Employees 
    on Jul 28, 2020 4:51 AM

    Hi Hiroyuki-san,

    The closest typical application is on page 38 of datasheet and your best reference. The observation you see is normal because duty cycle increases as input voltage decreases so there is more chance for inductor current to hit current limit. Please make sure that inductor current is below and with margin from its limit. Consider increasing inductance, or switching frequency. Please verify your design with LTspice.

  • 0
    •  Analog Employees 
    on Jul 28, 2020 4:52 AM

    Hi Hiroyuki-san,

    The closest typical application is on page 38 of datasheet and your best reference. The observation you see is normal because duty cycle increases as input voltage decreases so there is more chance for inductor current to hit current limit. Please make sure that inductor current is below and with margin from its limit. Consider increasing inductance, or switching frequency. Please verify your design with LTspice.